(1) Field of the Invention
This invention relates to injection molding machines, and more particularly to a systematized injection molding machine employing a die carriage for transferring a die set or sets to and from an injecting station and at least a station which performs a post-injection treatment in a continuous injection molding process.
(2) Description of the Prior Art
Injection molding is employed widely for the production of various articles, for example, for the production of multi-layered resinous sheet materials for instrument panels or door panels of motor vehicles, which are usually composed of an injection-molded base material M and a facing material F which is adhered integrally on the surface of the molded material M and which consists of a cushioning layer F.sub.1 of a foamed synthetic resin and a decorative skin layer F.sub.2 of polyvinyl chloride or the like as shown particularly in FIGS. 2 and 3.
Heretofore, the multi-layered resinous moldings of the above-mentioned construction have been produced by a process as illustrated in FIG. 1. Namely, in the first stage, a base material is produced by injection molding by the use of an injection molding machine and a die therefor. The molded base which is ejected from a die is then fixed on a jig of an adhesive applicator and coated with an adhesive on its surfaces. After predrying the coated adhesive, the base material is fed to a stamp press machine and set on a jig of the machine, preheating the upper and lower dies of the press machine, and then a facing material is fed to the machine in a similar manner to adhere the same on the surface of the molded base material by stamp pressing. The base molding covered with the facing material is then removed from the stamp press and fed to a trimmer where protruding hems of the facing material are trimmed off to obtain a predetermined multi-layered resin molding.
In the conventional process described above, the operations in the respective stages are performed independently of each other, so that it has been necessary to provide in each stage a jig for fixing the molded material to be processed. In addition, different die sets are used respectively in the injection molding machine, stamp press and trimmer, completely ejecting the molded material from the die of the molding machine after injection molding for transfer to the stamp press. It follows that there has to be employed a molding machine with a die clamp mechanism of large capacity and stroke length for the ejection of the molded article, thus incurring a high equipment cost. Moreover, the plasticized resinoid which is injected at a temperature of T.sub.3 has to be cooled sufficiently down to a temperature T.sub.1 in the stage of injection molding to permit ejection of the molded material, heating again the material to a level T.sub.2 from the ejection temperature T.sub.3 for predrying the coated adhesive or in preparation for the stamp pressing, resulting in a redundant production cycle with large heat and time losses and thus in a high production cost.